This invention relates in general to the handling of discrete pieces of flexible sheet material and more particularly to a machine for separating such pieces of sheet material when they are face to face in marginal registration and directing them to a desired location.
Printing magazines and similar publications involves a considerable amount of material handling. Large offset presses deliver the printed material as folded signatures which are arranged in stacks by the machine. Workmen remove the stacks from the presses and deposit them on pallets on which they are stored or the workmen may bind short stacks of the signatures together with bands to form longer bundles or logs. Since the bands maintain the signature under compression, the bundles or logs conserve storage space. By reason of the storage, one or two presses may produce all the signatures required for a magazine.
Once all of the signatures for the magazine are available, workmen break the stacks or bundles into smaller stacks called hand lifts and introduce the hand lifts into a binding machine which assembles their signatures in the proper order into a magazine. The typical binding machine has a succession of pockets, one for each signature required by the publication. Each pocket holds a stack of like signatures no more than about 14 inches tall. Binding machines as a whole are quite temperamental, and underfeeding or overfeeding the pockets on such machines can cause misfeeds. For example, if a pocket has too many signatures, the weight of those signatures inhibits the extracting mechanism from removing signatures, whereas too few signatures increases the chances of a double extraction. As a result, a binding machine requires several workmen to monitor its pockets, and to supply each of those pockets with a limited amount of signatures when it becomes low. This is manual labor, and while not overly difficult, it may lead to a physical ailment known as carpal tunnel syndrome, which is very painful. It requires expensive surgery for correction and even then the condition may reoccur.
Stream feeders exist for feeding the pockets of binding machines, but the machines of current manufacture operate on an incremental basis, so rarely do the pockets they feed contain the optimum number of signatures. Moreover, they are in themselves difficult to feed, and require excessive amounts of compressed air, which makes them expensive to operate.
The present invention resides in a stream feeder for removing signatures from a bundle or stack that exists in the form of an edge-standing array and delivering those signatures to another location, such as a pocket of a binding machine, in a continuous stream, indeed a stream which may be adjusted to match the demand at the location at which the signatures are required. It will thus maintain the pocket of a binding machine at an optimum level and thereby reduce the incidence of misfeeds from that pocket. Multiple stream feeders enable a single workman to service more pockets with less effort, and to avoid the motions which contribute to carpal tunnel syndrome. The stream feeder is quite compact, and therefore occupies little floor space. Moreover, it requires relatively little compressed air and is otherwise inexpensive to operate.